Adcom GFA-7700 Manual Do Utilizador

6

The GFA-7700 is a very high power amplifier and as such must be directly connected to the wall outlet 

or an appropriate surge protector or AC line conditioner. It must never be connected to the “switched” 

outlets on the rear panel of a pre-amplifier. Usually this would mean that when you turn on/off 

your pre-amplifier you would have to turn on/off your power amplifier separately. We have however 

provided the ability to control the OFF/ON function of the GFA-7700 by a 12Volt DC output jack on the 

rear of certain ADCOM pre-amplifiers and tuner pre-amplifiers. When using this feature the front panel 

Power Switch must be left in the in “on” position. To connect you will need a monaural mini phone plug 

to monaural mini phone plug cable of appropriate length (not included) to reach from the rear panel of 

the amplifier to the rear panel of the pre-amplifier. Contact your dealer for information on using this 

feature with ADCOM and other brand pre-amplifiers. Although 12VDC is optimal, the circuit will operate 

from approx. 5 to 30VDC. Center conductor (tip) is positive (+).

The AC Fuse protects the electronic circuits of the GFA-7700. Normally, this fuse 

will fail only if there is an overload within the GFA-7700. It may, however, fail if the 

amplifier attempts to deliver very high power into very low-impedance loudspeakers. 

In either case, BE SURE TO REPLACE THE AC Fuse ONLY WITH AN EXACT REPLACEMENT 

FUSE. The proper fuse values are:

 

Fuse Rating 

BUSS

®

 

Littlefuse

®

For 115 volt operation ....... 15 Amp 250 Volt .......... AGC-5/250V.................. (3AG) 312005/250V

For 230 volt operation ....... 8 Amp 250 Volt ............ AGC-3/250V.................. (3AG) 312003/250V

Before attempting to replace a failed fuse, be certain to unplug the AC Power Cord from the AC wall 

outlet to prevent possible electrical shock. Replace the AC Fuse only with one identical in type and 

rating as printed on the rear panel. DO NOT USE ANY SUBSTITUTE FUSES WITH DIFFERENT RATINGS OR 

VALUES. Failure to observe this precaution may cause serious damage to the amplifier circuits, MAY 

CREATE A FIRE HAZARD, AND MAY VOID THE WARRANTY.

If the Power LED (7) does not glow, it may be an indication that the AC fuse has blown. If you are using 

the 12VDC Triggering feature (above) it may be possible that there is a problem with that connection. 

To determine if the problem is caused by a malfunction in the 12VDC system, remove the small plug 

inserted into the 12VDC Triggering jack. Press the front panel power switch to turn off the amp, and 

immediately re-press the power switch. If the problem is caused by the 12VDC triggering circuit the 

amp will turn on and the LED will glow. DO NOT attempt repair of the 12VDC system. If you are not 

sure, or the amplifier displays other symptoms, please consult the RESOLVING PROBLEMS section on 

page 13. To remove the fuse-holder cap, you will need a 1⁄4” standard flat-blade screwdriver. Place the 

screwdriver in the recessed slot in the cap. Turn the cap 1/8-turn counter-clockwise, until the cap pops 

out towards you. Grasp the cap with your fingers and pull it completely out. The fuse is inserted in the 

back of the cap; gently pull it free.

Since the fuse has a ceramic body, you cannot visually examine the fuse element. It is therefore suggested 

that you replace it with an identical substitute or bring the fuse to your Adcom dealer so they may check 

its integrity. To replace the fuse, insert it in the back of the fuse-holder cap. Place the cap into the fuse-

holder. Place the screwdriver in the recessed slot, gently press in and turn 1/8-turn clockwise.

The AC cord provides power to operate all the GFA-7700’s circuits. Its plug can be connected to a 

standard wall outlet provided the outlet supplies a voltage compatible with the power requirements 

printed on the rear panel of the GFA-7700.